Method and device for referencing the position of an actuating element

Abstract

In a method for referencing the position of an actuating element of a functional unit, in particular of a clutch in the drivetrain of a vehicle, the attainment of a reference position of the actuating element is assessed for plausibility in that it is checked whether a variable which can be applied to the actuating element varies in a predetermined way in a predetermined spacing of the position of the actuating element from the reference position.

Description

[0001]This application is a continuation of prior International Application PCT / DE2007 / 000124, filed Jan. 25, 2007, which is hereby incorporated by reference herein.[0002]The invention relates to a method and device for referencing the position of an actuating element of a functional unit, especially a clutch in the drivetrain of a motor vehicle.BACKGROUND[0003]In the motorized actuation of functional units using an actuating element in which the function of the functional unit changes, e.g., in proportion to the position of the actuating element, it is frequently necessary to reference the position of the actuating element so that the precise position of the actuating element is known in a control unit. An example of this is the motorized actuation of a clutch in which the position of a clutch lever determines the torque transferability of the clutch. A precise knowledge of the torque transferability of the clutch is important to precisely control or regulate starting and shifting....

AI Technical Summary

Benefits of technology

The present invention provides a method and device for increasing the safety of referencing the position of an actuating element of a functional unit, especially a clutch in the drivetrain of a motor vehicle. The method involves checking the position of the actuating element by detecting changes in a variable that occurs when the actuating element reaches a predetermined distance from its reference position. The variable can be the actuation force required to position the actuating element or the speed of the actuating element. The method also includes evaluating the plausibility position of the actuating element and the reference position of the actuating element to increase overall reliability. The device includes an actuator, an incremental sensor, a referencing device, a plausibility device, a control unit, and a comparator to compare the actual plausibility position with the target plausibility position and save the counts of the incremental sensor as valid if the actual plausibility position deviates from the target plausibility position by less than a predetermined value. The invention can be used in various functional units of a motor vehicle.

Problems solved by technology

With referencing that uses stops and thereby recognizes that the actuating element does not move despite the force exerted by the actuator on the actuating element, there is a danger of incorrectly identifying a blockage as a reference position in a transmission path in which the actuating element is located.

Particularly when actuating clutches, this can cause hazardous operating conditions since the vehicle may for example unintentionally drive away.

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